1. Field of the Invention
The present invention relates generally to storage area networks, and in particular to data traffic management in a storage area network (SAN).
2. Background Information
Storage environments for enterprises are becoming increasingly complex as storage demands increase, and further due to an increasing number of hardware devices and subsystems included in SANs to meet such growing storage demands. A SAN typically includes a collection of one or more storage subsystems (storage controllers) connected by switches and connection fabrics to host systems. Each such storage subsystem includes a collection of one or more input/output (IO) ports through which it is connected to the fabrics. For a host to access a storage volume residing on a storage subsystem, one or more ports on the storage subsystem are chosen and paired with ports on the host. Thereafter, all the IO traffic initiated by that host to that storage volume flows through the designated ports.
Multiple workloads can use a particular port on a storage subsystem. Such allocation may initially suffice, but over time workloads experience growth or changes in usage patterns. If one or more workloads incur spikes in usage or grow over time, then the port(s) they are assigned to can become overloaded. This leads to performance degradation, not just for the spiking workload, but for all the workloads that utilize that port.
In such scenarios, moving one or more volumes of a workload from a storage subsystem with an overloaded port to another storage subsystem in the SAN may help mitigate the overload situation. However, migrating data is a complex and costly operation, and the cost increases depending on the amount of data that needs to be migrated.